I've been a console gamer this generation, and never really been a PC gamer since I don't have very powerful hardware, I actually have a piece of sh** . Do I have to worry about getting into games for things like Call of Duty for example? I don't want to just play one game mode and have a certain game have like 4 people in it (I'm not a COD fanboy, I like battlefield better, I know Counter Strike and such is better too, but I like to play COD every once in a while) Is there a healthy population for games like Call of Duty? I like to play with friends on xbox live but... alot of the time no one is really on anyways, I've got people to play with on PC too.

I'm really looking forward to Diablo 3 and the new Starcraft 2 expansion and some other PC only stuff... I'm just worried about games not having enough players that i can go into a game, choose a game mode of my choice and not be stuck with half full games. :P

With all the games you listed, I don't think you'll have any problems whatsoever finding players at any time of the day. All the games you listed still have very large communities and thousands of servers. If you were getting into something like BF2 or 2142, it'd be a different story, but CS, CS:S, COD4, Black Ops, BC2, etc... Are all still highly played games.

You also have free titles like League Of Legends, World Of Tanks, and Team Fortress 2 that also have large communities.

Take a look at the top games on Xfire, might give you a good idea as to what is played the most daily. Of course, you also have people who exclusively use Steam, or don't use a client at all. But still, it'll give you an idea.

for battlefield there's a hefty gaming community, COD not so much. When i decide to play MW2 it takes maybe 2-5 minutes to get matched in to a game because of that, BO is a bit better because theres a server browser so you can choose what game you want to enter.

Starcraft 2 is flourishing, especially competitive. Being one of very few competitive PC games left, if you're into that kind of thing, then its a great option. If you need someone to play with or against for SC2, lemme know. This applies to anyone who plays it as well, from noob thats never played an RTS, or Master rank, feel free. Cheers.